The present invention is directed to a method and apparatus for the automated discharge of treated sewage sludge from bins, as part of a sludge handling system.
In the treatment of sewage sludge so that it can meet the various criteria of the U.S. Environmental Protection Agency, so that the sewage sludge can be returned to the earth as fertilizer, or in some cases be used as ground fill, it has become commonplace that the sludge is first treated to remove pathogens, or at least reduce the pathogens in the sludge to an EPA acceptable level and to reduce the attractiveness of the sludge to vectors such as rats, mice, flies, etc., as well as to reduce the odors that may otherwise emanate from the sludge. The sludge generally has both solid and liquid components. Often, the sludge is dewatered to produce a higher solids content. The solids content of the sludge can vary, such that the physical characteristics of the sludge can range from a viscous, colloidal liquid to a dry cake or clay-like texture.
Some of the methods and apparatus for treating sludge, to which the present invention is addressed include the following patents, all of which are herein incorporated by reference:
5,013,4585,186,8405,229,0115,346,6165,401,4025,405,5365,433,8445,554,2795,618,4425,681,4815,783,0735,851,4047,669,3487,416,673
In accordance with the present invention, dewatered sludge is delivered to a conveyor device that can be any of various types, such as a belt conveyor, a screw conveyor, a pump for pumping sludge through a duct or tube, or any other conveyor devices that supplies sludge to a gravity flow bin. Preferably, a plurality of conveying devices are used, each supplying sludge to a different gravity flow bin. One such apparatus for delivering dewatered sludge to a conveyor mechanism for, in turn, delivering sludge to one or more gravity flow bins, is disclosed in U.S. Pat. No. 6,447,674, the complete disclosure of which is herein incorporated by reference.
It is known to use an arcuately configured discharge arm, sweeping across the floor of the silo or bin, to engage the sludge in the silo and move it toward the central discharge opening.